JPH04337359A - Infrared-absorptive compound and optical recording medium using the same - Google Patents

Abstract

PURPOSE:To provide the title compound having significant absorption band in the infrared region, large in adsorption coefficient, good in solubility, useful for optical recording media, and capable of giving said media durability and light stability. CONSTITUTION:The objective compound of formula I or II (R1 to R8 are each H or monovalent organic residue; R1 and R2, R3 and R4, R5 and R6, and/or R7 and R8 may be combined into five- or six-membered ring; X is S, relevant hetero, or five-membered heterocycle of formula III which may be substituted with lower alkyl or halogen; Y is anoin). For example, the present compound of the formula I or II can be obtained by the following process: a reaction is made between a compound of formula IV and a second compound of formula V into a compound of formula VI, which is then reduced into an amino modification of formula VII. This compound is put to selective substitution (e.g. by alkylation or alkenylation) followed by oxidation.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an infrared absorbing compound and an optical recording medium using the same, and in particular an infrared absorbing compound and its use that improve light resistance and durability stability during reproduction in optical discs or optical cards. Regarding the optical recording medium used.

0002

[Prior Art] Generally, optical disks and optical cards are
Small (eg, about 1 μm) optically detectable pits formed in a thin recording layer on a substrate can be formed in the form of spirals or circular and linear tracks to store high density information. To write information on such optical disks and optical cards, a focused laser is scanned on the surface of the laser sensitive layer, and only the surface irradiated with this laser beam forms pits, and these pits are shaped into spirals, circles, and shapes. Formed in the form of a straight track.

Laser sensitive layers can absorb laser energy to form optically detectable pits. For example, in the heat mode recording method, the laser sensitive layer absorbs thermal energy and can form small depressions (pits) at that location by evaporation or melting. In another heat mode recording method, absorption of irradiated laser energy can form pits having an optically detectable density difference at that location.

[0004] Here, by using an organic dye thin film as a recording layer with high reflectance, it is possible to set the optical contrast of recording pits to be high. For example, when using polymethine dyes, azulene dyes, cyanine dyes, pyrylium dyes, etc., which have high light absorption to laser light, as the organic dye thin film, metallic luster (reflectance of 10 to 50%
) is obtained, and an optical recording medium capable of laser recording and reflective reading is obtained. In particular, use of a semiconductor laser with an oscillation wavelength of 600 to 900 nm as a laser light source has the advantage that the device can be made smaller and lower in cost. However, organic dye thin films generally have a problem in that their recording and reproducing characteristics and storage stability deteriorate because of their tendency to undergo material changes when exposed to heat and light.

Furthermore, many proposals have already been made to improve the recording and reproducing characteristics and storage stability by adding infrared absorbing compounds such as aminium salts and diimonium salt compounds to organic dye thin films. However, when these aminium salt/diimonium salt compounds are included in an organic dye thin film, there is a problem in that they lower the reflectance of the thin film and lower the recording sensitivity as an optical recording medium.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and its purpose is to provide a material with a large absorption region in the infrared region and a large extinction coefficient. Another object of the present invention is to provide a novel infrared absorbing compound with good solubility.

Another object of the present invention is to provide an optical recording medium in which the novel infrared absorbing compound of the present invention is used in an optical recording medium that has significantly increased durability and light stability during repeated reproduction. It is in.

[0008]

[Means for Solving the Problems] That is, the present invention provides an infrared absorbing compound represented by the following general formula [I] or general formula [II], and the above general formula [I] and/or general formula [II]. This is an optical recording medium characterized by having an organic dye thin film containing an infrared absorbing compound represented by:

[0009]

[C4]

0010

[C5]

(In the formula, R1 to R8 represent a hydrogen atom or a monovalent organic residue. R1 to R8 may be different or the same. Also, R1 and R2
, R3 and R4 , R5 and R6 and R7 and R8
You may form a 5-membered ring, a 6-membered ring, or a 7-membered ring by the combination. X represents sulfur and related heteroatoms, with formula [I
II] forms a 5-membered hetero ring. This 5-membered heterocyclic ring may be substituted with a lower alkyl group, a lower alkoxy group, a halogen group, a hydroxyl group or a cyano group. Y- represents an anion. )

0012

[C6]

The above general formula [I] and general formula [II]
In, R1 to R8 represent a hydrogen atom or a monovalent organic residue. Examples of monovalent organic residues include alkyl groups such as methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, t-butyl group, and n-butyl group. amyl group, t-amyl group,
n-hexyl group, n-octyl group, t-octyl group, etc., and other alkyl groups, such as substituted alkyl groups, such as 2-hydroxyethyl group, 3-hydroxypropyl group, 4-hydroxybutyl group, 2-acetoxyethyl group, carboxymethyl group, 2-carboxyethyl group, 3-carboxypropyl group, methoxyethyl group, ethoxyethyl group, methoxypropyl group, etc. Alkenyl groups include, for example, vinyl group, propenyl group, butenyl group, pentenyl group, hekyanyl group, heptenyl group,
Examples of aralkyl groups such as octenyl group include benzyl group, p-chlorobenzyl group, p-methylbenzyl group, 2-phenylmethyl group, 2-phenylpropyl group, 3
Examples of alkynyl groups include -phenylpropyl group, α-naphthylmethyl group, β-naphthylethyl group, etc.
These include propargyl group, butynyl group, pentynyl group, hexynyl group, etc.

R1 to R8 may be different or the same.

[0015] Furthermore, R1 and R2, R3 and R4,
The combination of R5 and R6 and R7 and R8 may form a substituted or unsubstituted 5-, 6-, or 7-membered ring, and the 5-membered ring is a pyrrolidine ring, the 6-membered ring is a piperidine ring, The morpholine ring, the tetrahydropyridine ring, and the 7-membered ring include a cyclohexylamine ring. These rings may be the same or different.

X represents sulfur and related heteroatoms. Examples of heteroatoms include S, O, NR9 (R9 is R
1), Se, Te, etc., each forming a five-membered hetero ring such as a thiophene ring, a furan ring, a pyrrole ring, a selenol ring, and a tellurol ring. This 5-membered heterocyclic ring may be substituted with a lower alkyl group, a lower alkoxy group, a halogen group, a hydroxyl group, a cyano group, or the like.

Y- is a chloride ion, bromide ion, iodine ion, perchlorate ion, nitrate ion, benzenesulfonate ion, p-toluenesulfonate ion, methylsulfate ion, ethylsulfate ion, propyl Sulfate ion, tetrafluoroborate ion, tetraphenylborate ion, hexafluorophosphate ion, benzenesulfinate ion, acetate ion, trifluoroacetate ion, propionacetate ion, benzoate ion , oxalate ion, succinate ion, malonate ion, oleate ion, stearate ion, citrate ion, monohydrogen diphosphate ion, dihydrogen monophosphate ion, pentachlorotin Salt ion, chlorosulfonate ion, fluorosulfonate ion, trifluoromethanesulfonate ion, hexafluoroarsenate ion, hexafluoroantimonate ion, molybdate ion, tungstate ion, titanate ion ion, anion such as zirconate ion.

The method for producing the infrared absorbing compound of the present invention is described in US Pat. No. 3,251,881 and US Pat. No. 357.
The methods described in No. 5871, US Pat. No. 3,484,467, JP-A-61-69991, etc. can be used. For example, it can be manufactured by the following process.

[0019]

[C7]

[0020] After the amino compound obtained by the above Ullmann reaction and reduction reaction is substituted by selective substitution, for example, by alkylation, alkenylation, aralkylation, or alkynylation, the final product can be obtained by oxidation reaction. .

If R1 to R8 are asymmetric, it is necessary to carry out the alkylation in multiple stages, and from the viewpoint of cost, it is preferable that R1 to R8 are the same.

Next, specific examples of the infrared absorbing compound represented by the general formula [I] or the general formula [II] according to the present invention will be given. For simplicity,

[0023]

[Chemical formula 8]

[0024]

[Chemical formula 9]

[0025] In the present invention, R1 to R8 are R1, R2, R3, R4, R5, R6, R
7 and R8 are shown.

[0026]

[Chemical formula 10]

[0027]

[Chemical formula 11]

[0028]

[Chemical formula 12]

[0029]

[Chemical formula 13]

[0030]

[Chemical formula 14]

[0031]

[Chemical formula 15]

[0032]

[Chemical formula 16]

[0033]

[Chemical formula 17]

[0034]

[Chemical formula 18]

[0035]

[Chemical formula 19]

[0036]

[C20]

[0037]

[C21]

[0038]

[C22]

[0039]

[C23]

[0040]

[C24]

[0041]

[C25]

[0042]

[C26]

[0043]

[C27]

[0044]

[C28]

[0045]

[C29]

[0046]

[C30]

[0047]

[Chemical formula 31]

[0048]

[C32]

[0049]

[Chemical formula 33]

[0050]

[C34]

[0051]

[C35]

[0052]

[C36]

[0053]

[C37]

[0054]

[C38]

[0055]

[C39]

[0056]

[C40]

[0057]

[C41]

[0058]

[C42]

[0059]

[C43]

[0060]

[C44]

[0061]

[C45]

[0062]

[C46]

[0063]

[C47]

[0064]

[C48]

[0065]

[C49]

The aminium salt compound or diimonium salt compound exemplified above has a maximum absorption wavelength of 900 nm.
It has a large absorption peak with an extinction coefficient of tens of thousands to hundreds of thousands.

[0067] In addition to being used as a material for optical recording media, such infrared absorbing compounds are used for heat insulating films, sunglasses, and the like.

Furthermore, the infrared absorbing compound of the present invention can be used by being included in an organic dye thin film of an optical recording medium.

As the near-infrared absorbing dye that forms the organic dye thin film used in combination with these infrared absorbing compounds as an optical recording medium, commonly known dyes are used, such as cyanine dyes and merocyanine. pigments, croconium pigments, squalium pigments, azulenium pigments, polymethine pigments, naphthoquinone pigments, pyrylium pigments, phthalocyanine pigments, naphthalocyanine pigments,
These include naphtolactam pigments.

The amount of the infrared absorbing compound consisting of the aminium salt compound of the general formula [I] and/or the diimmonium salt compound of the general formula [II] to be added to these dyes is determined based on the total solid content of the recording layer. 1 to 60% by weight
, preferably 5 to 40% by weight, more preferably 5 to 30% by weight
Weight % is appropriate.

In addition to these compounds, a binder may be contained in the recording layer consisting of an organic dye thin film. Examples of binders include cellulose esters such as nitrocellulose, cellulose phosphate, cellulose sulfate, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose myristate, cellulose parimitate, cellulose acetate/propionate, cellulose acetate/butyrate, and methylcellulose. , cellulose ethers such as ethyl cellulose, propyl cellulose, butyl cellulose, polystyrene, polyvinyl chloride, polyvinyl acetate,
Vinyl resins such as polyvinyl butyral, polyvinyl acetal, polyvinyl alcohol, polyvinylpyrrolidone, copolymer resins such as styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-butadiene-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, polymethyl Acrylic resins such as methacrylate, polymethyl acrylate, polybutyl acrylate, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyacrylonitrile,
Polyesters such as polyethylene terephthalate, poly(4,4'-isopropylidenediphenylene-co-1)
, 4-cyclohexylene dimethylene carbonate), poly(ethylenedioxy-3,3'-phenylene thiocarbonate), poly(4,4'-isopropylidene diphenylene carbonate-co-terephthalate), poly(4-cyclohexylene dimethylene carbonate),
, 4'-isopropylidene diphenylene carbonate)
, polyarylate resins such as poly(4,4'-sec-butylidene diphenylene carbonate), poly(4,4'-isopropylidene diphenylene carbonate-block-oxyethylene), or polyamides, polyimides, and epoxy resins. Polyolefins such as phenolic resins, polyethylene, polypropylene, and chlorinated polyethylene can be used.

The recording layer may also contain surfactants, antistatic agents, stabilizers, dispersible flame retardants, lubricants, plasticizers, and the like. Further, an undercoat layer may be provided between the recording layer and the substrate, and a protective layer may be provided on the recording layer.

The undercoat layer is used to provide solvent resistance, improve reflectance, or improve repeat playback.The protective layer is used to protect the recording layer from scratches, dust, dirt, etc., and to provide environmental stability to the recording layer. used for The materials used for these are mainly inorganic compounds, metals, or organic polymer compounds. Examples of inorganic compounds include SiO
2, MgF2, SiO, TiO2, ZnO, Ti
Metals such as N and SiN include, for example, Zn, Cu, and N.
i, Al, Cr, Ge, Se, Cd, etc., and organic polymer compounds such as ionomer resin, polyamide resin,
Vinyl resin, natural polymer, epoxy resin, silane coupling agent, silicone resin, liquid rubber, etc. can be used.

As the substrate, plastics such as polyester, polycarbonate, acrylic resin, polyolefin resin, phenol resin, epoxy resin, polyamide, polyimide, glass, or metals can be used.

Organic solvents that can be used during coating differ depending on whether it is in a dispersed or dissolved state, but generally include alcohols such as methanol, ethanol, and isopropanol, acetone, methyl ethyl ketone,
Ketones such as cyclohexanone and diacetone alcohol, amides such as N,N-dimethylformamide and N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, and methyl acetate. , esters such as ethyl acetate, butyl acetate, aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, trichloroethylene, benzene, toluene, xylene, monochlorobenzene, dichlorobenzene, etc. Aromatics or aliphatic hydrocarbons such as n-hexane and cyclohexanoligroin, fluorinated solvents such as tetrafluoropropanol and pentafluoropropanol, and the like can be used.

Coating can be carried out using coating methods such as dip coating, spray coating, spinner coating, bead coating, wire bar coating, blade coating, roller coating, and curtain coating. .

The thickness of the recording layer formed using such a solvent is 50 Å to 100 μm, preferably 200 Å to 1 μm.
μm is appropriate.

[0078]

[Examples] Next, examples of the present invention will be described.

Synthesis Example 2 0.5 mole of 5-diaminothiophene, 2.3 mole of p-nitrochlorobenzene, 1.2 mole of anhydrous potassium carbonate, and 10 parts (by weight) of copper powder were stirred in 600 parts of dimethylformamide. Reflux was carried out for 4 days. After the reaction, the reaction mixture was filtered, and the filtrate was thoroughly washed with dimethylformamide, water, and acetone, and then dried. reddish brown tetrakis (p-
Nitrophenyl)-2,5-diaminothiophene 105
I got the department.

25 parts of the compound obtained above were added into an autoclave together with 100 parts of dimethylformamide palladium-carbon hydrogenation catalyst, and 5.0 kg of hydrogen gas was added.
/cm2 and stirred at 90°C to 100°C until hydrogen absorption stopped.

After the reaction, the reaction solution was filtered, and the filtrate was washed with dimethylformamide, and then poured into 350 parts of ice water. After stirring for a while, the precipitate was collected. Recrystallize with ethanol dimethylformamide mixed solvent,
8 parts of tetrakis(p-aminophenyl)-2,5-diaminothiophene were obtained. Purity was measured by high performance liquid chromatography and found to be 95.6%.

Compound No. Synthesis of [I]-(A)-(5) 2 parts of the above amino compound were heated and stirred with 12 parts of dimethylformamide, 0.5 parts of anhydrous sodium bicarbonate, and 3.0 parts of n-propyl bromide at 100°C to 130°C. Did. After reacting for 36 hours, the reaction solution was poured into 100 parts of ice water and extracted with ethyl acetate. After drying, it was purified using a silica gel column. The amount obtained was 1.5 parts. Disappearance of absorption due to NH stretching vibration of the amino group was confirmed by infrared absorption analysis.

1.0 part of this compound was dispersed in 20 parts of acetone, and the equimolar amount of silver perchlorate was added while stirring. After reacting at room temperature for 1 hour, the precipitated silver was filtered off, the filtrate was diluted with isopropyl ether and allowed to stand, and the precipitated crystals were filtered out. The amount obtained was 0.8 parts.

Compound No. synthesized in this manner. [I
]-(A)-(5) was a compound having a large absorption region in the infrared region with an absorption maximum wavelength of 1005 nm and an extinction coefficient of 63,000.

Compound No. [II] Synthesis of -(A)-(5) Compound No. Tetrakis(p-dipropylaminophenyl)-2 used in the synthesis of [I]-(A)-(5),
1 part of 5-diaminothiophene was dispersed in 16 parts of acetone, and 2 times the mole of silver perchlorate was added while stirring. After reacting for 1 hour at room temperature, the precipitated silver was filtered off, and the filtrate was diluted with isopropyl ether. 0.5 parts of precipitated crystals were collected.

In the example explained above, the anion is perchloric acid, but if another anion is used, the desired compound can be easily obtained by using the corresponding silver salt. For example, AgSbF6, AgBF
4,AgSO4,AgNO3,AgSO3C6
Silver salts such as H4 CH3 and AgAsF6 can be used. In addition, it can also be obtained by electrolytic oxidation.

Synthesis Example 2 The reaction was carried out in the same manner as in Synthesis Example 1, except that 2,5-diaminothiophene used in Synthesis Example 1 was changed to 2,5-diaminofuran, and tetrakis(p-aminophenyl)
20 parts of -2,5-diaminofuran were obtained.

Compound No. Synthesis of [I]-(B)-(14) 3.8 parts of the amino compound obtained in Synthesis Example 2 were added with 25 parts of dimethylformamide, 1.1 parts of anhydrous sodium bicarbonate, and 4.2 parts of 2-methoxyethyl bromide. 100℃～13
The mixture was heated and stirred at 0°C. After reacting for 37 hours, the reaction solution was poured into ice water and extracted with ethyl acetate. After drying, it was purified using a silica gel column. The amount obtained was 3.4 copies. Disappearance of absorption due to NH stretching vibration of the amino group was confirmed by infrared absorption analysis.

One part of this compound was dispersed in 18 parts of acetone, and equimolar amount of silver hexafluoroantimonate was added while stirring. After reacting at room temperature for 1 hour, the precipitated silver was filtered off, the filtrate was diluted with isopropyl ether and allowed to stand, and the precipitated crystals were filtered out. The amount obtained was 0.8 parts. Furthermore, the compound had a maximum absorption wavelength of 1070 nm and an extinction coefficient of 70,000, and had large absorption in the infrared region.

Compound No. [II]-(B)-(4) Synthesis Compound No. [I]-(B)-(14) 0.5 part of tetrakis(p-dimethoxyethylaminophenyl)-2,5-diaminofuran obtained during the synthesis was dispersed in 11 parts of acetone while stirring. Two times the mole of silver perchlorate was added at room temperature, and the mixture was stirred for 1 hour. After the reaction, the precipitated silver salt was filtered out and thoroughly washed with acetone. After acetone was distilled off from the filtrate, it was washed with water and dried under reduced pressure. Yield is 0.
35 parts, it was an infrared absorbing compound with a maximum peak at 1081 nm and an extinction coefficient of 101,000.

Next, examples will be described in which infrared absorbing compounds represented by general formulas [I] and [II] are used as optical recording materials.

Example 1 On a polymethyl methacrylate (hereinafter abbreviated as "PMMA") substrate with a diameter of 130 mmφ and a thickness of 1.2 mm,
2P using epoxy-acrylate ultraviolet curing resin
A pregroup with a thickness of 30 μm was formed using the photopolymer method (photopolymer method), and IR-820 was added as a polymethine dye on top of the pregroup.
(manufactured by Nippon Kayaku) and the infrared absorbing compound No. [I]-(
A solution obtained by dissolving A)-(5) in 1,2-dichloroethane at a weight ratio of 80:20 was applied by spinner coating and dried to obtain an organic thin film layer with a thickness of 900 Å.

[0093] The optical recording medium thus prepared was mounted on a turntable, and the turntable was rotated by a motor.
While rotating at 800 rpm, information was written from the substrate side into the organic thin film recording layer at a recording power of 8 mW and a recording frequency of 3 MHz using a semiconductor laser with an oscillation wavelength of 830 nm.
Reproduction was performed with a readout power of 0.8 mW, and the reproduced waveform was subjected to spectral analysis (scanning filter, bandwidth 30
KHz) and the C/N ratio (carrier/noise ratio) was measured.

Next, the C/N ratio was measured after repeatedly reading out the portion recorded on the same recording medium under the above measurement conditions 105 times.

Furthermore, the reflectance (830n
m) and C/N ratio were measured. Further, the same recording medium was irradiated with xenon lamp light of 1000 W/m2 (300 to 900 nm) for 100 hours to perform a light resistance stability test, and then the reflectance (830 nm) and C/N ratio were measured. The results are shown in Table 1.

[0096]

[Table 1]

Examples 2 to 8 The polymethine dye and infrared absorbing compound used in Example 1 were replaced with the combinations of polymethine dye or azulenium dye and infrared absorbing compound shown in Table 2 below. Example 1
Recording media were produced in the same manner as in Example 2 to
No. 8 optical recording medium was used.

The optical recording media of Examples 2 to 8 above were measured in the same manner as in Example 1. The results are shown in Table 3.

Comparative Examples 1 and 2 The infrared absorbing compounds used in Examples 2 and 5 were [
Optical recording media were prepared and evaluated in the same manner as in Example 1, except that I]-(B)-(8) and [I]-(C)-(14) were removed. The results are shown in Table 3.

[0100]

[Table 2]

[0101]

[C50]

[0102]

[C51]

[0103]

[C52]

[0104]

[Table 3]

Examples 9 to 12 4 parts by weight of a mixture of combinations of organic dyes and infrared absorbing compounds shown in Table 4 below and 1 part by weight of nitrocellulose resin (OHALES Lacquer, manufactured by Daicel Chemical Co., Ltd.) were added. A solution mixed with 95 parts by weight of diacetone alcohol was applied using a spinner to form a pre-groove with a diameter of 130 m.
The organic thin film recording layer was coated on a polycarbonate substrate with mφ and thickness of 1.2 mm to obtain an organic thin film recording layer with a dry film thickness of 950 Å.

The optical recording medium thus produced was measured in the same manner as in Example 1. The results are shown in Table 5.

[0107]

[Table 4]

[0108]

[C53]

[0109]

[C54]

[0110]

[Table 5]

Examples 13 to 16 Pregrooves were formed on a wallet-sized 0.4 mm thick polycarbonate (hereinafter abbreviated as "PC") substrate by a heat press method, and the weight ratios shown in Table 6 below were formed. A solution prepared by mixing 2.5 parts of a mixture of an organic dye and an infrared absorbing compound in 97.5 parts of diacetone alcohol was coated using the bar coating method, and then dried to a thickness of 900 Å.
A recording layer was obtained. Furthermore, a wallet-sized thickness of 0.3 m is coated on top of this with an ethylene-acetate dry film.
An optical recording medium with an adhesive structure was produced by bonding mPC substrates together by a hot roll method.

[0112] The optical recording media of Examples 13 to 16 thus produced were mounted on a stage driven in the X-Y direction, and using a semiconductor laser with an oscillation wavelength of 830 nm, the optical recording medium of Examples 13 to 16 was exposed from the side of a 0.4 mm thick PC board. Information was written in the Y-axis direction on the organic thin film recording layer with a recording power of 3.5 mW and a recording pulse of 50 μsec, and was reproduced with a read power of 0.2 mW.

[0113]

[Math 1]

[0114] was measured.

Furthermore, the same optical recording medium produced under the above conditions was subjected to an environmental storage stability test under the same conditions as in Example 1.
A light resistance stability test was also conducted, and the reflectance and contrast ratio were then measured. The results are shown in Table 7.

Comparative Examples 3 and 4 Infrared absorbing compounds used in Examples 13 and 16, No.
[I]-(D)-(16), and [II]-(E)-
Optical recording media were produced and evaluated in the same manner as in Examples 13 and 14, except for excluding (12). The results are shown in Table 7.

[0117]

[Table 6]

[0118]

[C55]

[0119]

[C56]

[0120]

[Table 7]

[0121]

[Effects of the Invention] As explained above, the general formula [
The infrared absorbing compounds represented by [I] and [II] are
It has the advantages of having large absorption in the infrared region and a significantly large extinction coefficient (ε); (1) good solubility in general-purpose organic solvents;

[0122] When the infrared absorbing compound is incorporated into an organic dye thin film and used as an optical recording medium, (1)
Recording and reproducing characteristics with a clear threshold for laser power can be obtained without reducing the excellent properties of organic dyes such as high reflectance and high sensitivity.■ High stability against heat and light, and long-term storage. The advantage is that an optical recording medium with excellent properties and little reproduction deterioration can be obtained.

Claims (2)

[Claims] [Claim 1] The following general formula [I] or general formula [II]
] An infrared absorbing compound represented by. [Formula 1] [Formula 2] (wherein, R1 to R8 represent a hydrogen atom or a monovalent organic residue. R1 to R8 may be different or the same. Also, R1 and R2, R3 and R
4, R5 and R6, and R7 and R8 may form a 5-membered ring, a 6-membered ring, or a 7-membered ring. X represents sulfur and related heteroatoms, and formula [III] forms a 5-membered heterocyclic ring. This 5-membered heterocyclic ring is a lower alkyl group,
It may be substituted with a lower alkoxy group, halogen group, hydroxyl group or cyano group. Y- represents an anion. ) [Chemical formula 3] [Claim 2] General formula [I] according to claim 1 and/or
Or an optical recording medium characterized by having an organic dye thin film containing an infrared absorbing compound represented by the general formula [II].